An enhanced global positioning system and map navigation process, which incorporates the GPS position data and geospatial map data. This enhanced navigation process includes GPS-based efficient geospatial database access and query and a time-space filtering method to fully fuse the GPS position data and the geospatial map data to obtain enhanced navigation performance. The system features both portability and ease-of-use. It also accommodates mission specific database creation and value-adding techniques. The system includes personal navigation, land vehicle navigation, marine navigation, etc.

(a) receiving a measured position from a global positioning system receiver;

(b) retrieving geospatial data from a geospatial map database based on said measured position from said global positioning system receiver by using a tile index file, wherein said tile index file stores geographic extent information of tileswhich are geographically subdividing a coverage solely for a purpose of enhancing data management; wherein a geographic extent of an access area is compared with said geographic extent of said tiles to derive a plurality of involved tiles for saidaccess area;

(c) performing time-space filtering based on said measured position and said retrieved geospatial data from said geospatial map database to derive a displaying position for a user; wherein said measured position and a previous position and aprevious velocity are used to derive a true position for said user; and

(d) displaying a trajectory of said user on a graphic displaying unit, which tracks a motion of said user.

2. An enhanced global positioning system and map navigation process, as recited in claim 1, before the step (c), further comprising a step of displaying said retrieved geospatial data on said graphic displaying unit as a background.

3. An enhanced global positioning system and map navigation process, as recited in claim 2, after the step (c), further comprising a step of displaying an accurate position of said user on said graphic displaying unit as a mark.

4. An enhanced global positioning system and map navigation process, as recited as claim 3, before the step (b), further comprising the steps of:

(b-1) defining said access area based on said measured position from said global positioning system receiver and said geographic extent, wherein said measured position from said global positioning system receiver is a center of said access areaand said geographic extent is input by said user; and

(b-2) performing a GPS-based database matching process to derive an involved geospatial database, wherein said geographic extent of said access area is compared with a geographic extent of said geospatial database to check whether said accessarea is included in said geospatial database, intersects with said geospatial database, or is excluded from said geospatial database.

5. An enhanced global positioning system and map navigation process, as recited as claim 4, after the step (b), further comprising the step of performing a GPS-based primitive access process on said involved tiles, wherein said GPS-basedprimitive access comprises a GPS-based node access, a GPS-based edge access and a GPS-based area access, wherein said primitive includes a node, an edge and an area, wherein said node, said edge and said area in said involved tiles are retrieved.

6. An enhanced global positioning system and map navigation process, as recited in claim 5, wherein the step (c) further comprises the steps of:

(c-1) forming a predicted position by predicting a current position of said user based on said previous position and said previous velocity of said user from said global positioning system receiver; and

(c-2) calculating a true position of said user based on said predicted position of said user and said measured position from said global positioning system receiver, wherein said true position of said user is an average position of said predictedposition of said user and said measured position from said global positioning system receiver.

7. An enhanced global positioning system and map navigation process, as recited in claim 6, wherein the step (c) further comprises the steps of:

(c-3) computing a distance from said true position of said user to a road neighboring said true position of said user; and

(c-4) comparing said distance from said true position of said user to said road neighboring said true position of said user with a threshold, wherein said threshold is preset based on an accuracy of said global positioning system receiver, andsaid position mark of said user is displayed on said road when said distance from said true position of said user to said road neighboring said true position of said user is less than said threshold, wherein said position mark of said user is displayedat said calculated true position when said distance from said true position of said user to said road neighboring of said true position of said user is larger than said threshold.

8. An enhanced global positioning system and map navigation process, as recited in claim 4, wherein the step (c) further comprises the steps of:

(c-1) forming a predicted position by predicting a current position of said user based on said previous position and said previous velocity of said user from said global positioning system receiver; and

(c-2) calculating a true position of said user based on said predicted position of said user and said measured position from said global positioning system receiver, wherein said true position of said user is an average position of said predictedposition of said user and said measured position from said global positioning system receiver.

9. An enhanced global positioning system and map navigation process, as recited in claim 8, wherein the step (c) further comprises the steps of:

(c-3) computing a distance from said true position of said user to a road neighboring said true position of said user; and

(c-4) comparing said distance from said true position of said user to said road neighboring said true position of said user with a threshold, wherein said threshold is preset based on an accuracy of said global positioning system receiver, andsaid position mark of said user is displayed on said road when said distance from said true position of said user to said road neighboring said true position of said user is less than said threshold, wherein said position mark of said user is displayedat said calculated true position when said distance from said true position of said user to said road neighboring of said true position of said user is larger than said threshold.

10. An enhanced global positioning system and map navigation process, as recited as claim 2, before the step (b), further comprising the steps of:

(b-1) defining said access area based on said measured position from said global positioning system receiver and said geographic extent, wherein said measured position from said global positioning system receiver is a center of said access areaand said geographic extent is input by said user: and

(b-2) performing a GPS-based database matching process to derive an involved geospatial database, wherein said geographic extent of said access area is compared with a geographic extent of said geospatial database to check whether said accessarea is included in said geospatial database, intersects with said geospatial database, or is excluded from said geospatial database.

11. An enhanced global positioning system and map navigation process, as recited as claim 10, after the step (b), further comprising the step of performing a GPS-based primitive access process on said involved tiles, wherein said GPS-basedprimitive access comprises a GPS-based node access, a GPS-based edge access and a GPS-based area access, wherein said primitive includes a node, an edge and an area, wherein said node, said edge and said area in said involved tiles are retrieved.

12. An enhanced global positioning system and map navigation process, as recited in claim 11, wherein the step (c) further comprises the steps of:

(c-1) forming a predicted position by predicting a current position of said user based on said previous position and said previous velocity of said user from said global positioning system receiver; and

(c-2) calculating a true position of said user based on said predicted position of said user and said measured position from said global positioning system receiver, wherein said true position of said user is an average position of said predictedposition of said user and said measured position from said global positioning system receiver.

13. An enhanced global positioning system and map navigation process, as recited in claim 12, wherein the step (c) further comprises the steps of:

(c-3) computing a distance from said true position of said user to a road neighboring said true position of said user; and

(c-4) comparing said distance from said true position of said user to said road neighboring said true position of said user with a threshold, wherein said threshold is preset based on an accuracy of said global positioning system receiver, andsaid position mark of said user is displayed on said road when said distance from said true position of said user to said road neighboring said true position of said user is less than said threshold, wherein said position mark of said user is displayedat said calculated true position when said distance from said true position of said user to said road neighboring of said true position of said user is larger than said threshold.

14. An enhanced global positioning system and map navigation process, as recited in claim 10, wherein the step (c) further comprises the steps of:

(c-1) forming a predicted position by predicting a current position of said user based on said previous position and said previous velocity of said user from said global positioning system receiver; and

(c-2) calculating a true position of said user based on said predicted position of said user and said measured position from said global positioning system receiver, wherein said true position of said user is an average position of said predictedposition of said user and said measured position from said global positioning system receiver.

15. An enhanced global positioning system and map navigation process, as recited in claim 14, wherein the step (c) further comprises the steps of:

(c-3) computing a distance from said true position of said user to a road neighboring said true position of said user; and

(c-4) comparing said distance from said true position of said user to said road neighboring said true position of said user with a threshold, wherein said threshold is preset based on an accuracy of said global positioning system receiver, andsaid position mark of said user is displayed on said road when said distance from said true position of said user to said road neighboring said true position of said user is less than said threshold, wherein said position mark of said user is displayedat said calculated true position when said distance from said true position of said user to said road neighboring of said true position of said user is larger than said threshold.

16. An enhanced global positioning system and map navigation process, as recited as claim 1, before the step (b), further comprising the steps of:

(b-1) defining said access area based on said measured position from said global positioning system receiver and said geographic extent, wherein said measured position from said global positioning system receiver is a center of said access area,and said geographic extent is input by said user; and

(b-2) performing a GPS-based database matching process to derive an involved geospatial database, wherein said geographic extent of said access area is compared with a geographic extent of said geospatial database to check whether said accessarea is included in said geospatial database, intersects with said geospatial database, or is excluded from said geospatial database.

17. An enhanced global positioning system and map navigation process, as recited as claim 16, after the step (b), further comprising the step of performing a GPS-based primitive access process on said involved tiles, wherein said GPS-basedprimitive access comprises a GPS-based node access, a GPS-based edge access and a GPS-based area access, wherein said primitive includes a node, an edge and an area, wherein said node, said edge and said area in said involved tiles are retrieved.

18. An enhanced global positioning system and map navigation process, as recited in claim 17, wherein the step (c) further comprises the steps of:

(c-1) forming a predicted position by predicting a current position of said user based on said previous position and said previous velocity of said user from said global positioning system receiver;

(c-2) calculating a true position of said user based on said predicted position of said user and said measured position from said global positioning system receiver, wherein said true position of said user is an average position of said predictedposition of said user and said measured position from said global positioning system receiver.

19. An enhanced global positioning system and map navigation process as recited in claim 18, wherein the step (c) further comprises the steps of:

(c-3) computing a distance from said true position of said user to a road neighboring said true position of said user; and

(c-4) comparing said distance from said true position of said user to said road neighboring said true position of said user with a threshold, wherein said threshold is preset based on an accuracy of said global positioning system receiver, andsaid position mark of said user is displayed on said road when said distance from said true position of said user to said road neighboring said true position of said user is less than said threshold, wherein said position mark of said user is displayedat said calculated true position when said distance from said true position of said user to said road neighboring of said true position of said user is larger than said threshold.

20. An enhanced global positioning system and map navigation process, as recited in claim 16, wherein the step (c) further comprises the steps of:

(c-1) forming a predicted position by predicting a current position of said user based on said previous position and said previous velocity of said user from said global positioning system receiver; and

(c-2) calculating a true position of said user based on said predicted position of said user and said measured position from said global positioning system receiver, wherein said true position of said user is an average position of said predictedposition of said user and said measured position from said global positioning system receivers.

21. An enhanced global positioning system and map navigation process as recited in claim 20, wherein the step (c) further comprises the steps of:

(c-3) computing a distance from said true position of said user to a road neighboring said true position of said user; and

(c-4) comparing said distance from said true position of said user to said road neighboring said true position of said user with a threshold, wherein said threshold is preset based on an accuracy of said global positioning system receiver, andsaid position mark of said user is displayed on said road when said distance from said true position of said user to said road neighboring said true position of said user is less than said threshold, wherein said position mark of said user is displayedat said calculated true position when said distance from said true position of said user to said road neighboring of said true position of said user is larger than said threshold.

22. An enhanced global positioning system and map navigation process, as recited in claim 1, wherein the step (c) further comprises the steps of:

(c-1) forming a predicted position by predicting a current position of said user based on said previous position and said previous velocity of said user from said global positioning system receiver; and

(c-2) calculating a true position of said user based on said predicted position of said user and said measured position from said global positioning system receiver, wherein said true position of said user is an average position of said predictedposition of said user and said measured position from said global positioning system receiver.

23. An enhanced global positioning system and map navigation process, as recited in claim 22, wherein the step (c) further comprises the steps of:

(c-3) computing a distance from said true position of said user to a road neighboring said true position of said user; and

(c-4) comparing said distance from said true position of said user to said road neighboring said true position of said user with a threshold, wherein said threshold is preset based on an accuracy of said global positioning system receiver, andsaid position mark of said user is displayed on said road when said distance from said true position of said user to said road neighboring said true position of said user is less than said threshold, wherein said position mark of said user is displayedat said calculated true position when said distance from said true position of said user to said road neighboring of said true position of said user is larger than said threshold.

(b) retrieving geospatial data from a geospatial map database based on said position from said global positioning system receiver through the steps of:

(b-1) defining an access area based on said position from said global positioning system receiver and a geographic extent, wherein said position from said global positioning system receiver is a center of said access area, and said geographicextent is input by a user;

(b-2) performing a GPS-based database matching process to derive an involved geospatial database, wherein said geographic extent of said access area is compared with a geographic extent of said geospatial database to check whether said accessarea is included in said geospatial database, intersects with said geospatial database, or is excluded from said geospatial database;

(b-3) performing a GPS-based involved tile finding process on said involved databases to derive involved tiles, wherein said tile is geographically subdividing a coverage solely for a purpose of enhancing data management, wherein a tile indexfile is used to-retrieve a geographic extent of said tile, and said geographic extent of said access area is compared with said geographic extent of said tile to check whether said access area is included in said tile, intersects with said tile, or isexcluded from said tile; and

(b-4) performing a GPS-based primitive access process on said involved tiles, wherein said GPS-based primitive access comprises a GPS-based node access, a GPS-based edge access and a GPS-based area access, wherein said primitive includes a node,an edge, and an area, wherein said node, said edge, and said area in said involved tiles are retrieved;

(c) performing time-space filtering based on said position and said retrieved geospatial data from said geospatial map database to derive a displaying position for said user; and

(d) displaying a trajectory of said user on a graphic displaying unit, which tracks a motion of said user.

25. An enhanced global positioning system and map navigation process, as recited in claim 24, wherein the step (c) further comprises the steps of:

(c-1) forming a predicted position by predicting a next position of said user based on a current position and velocity of said user from said global positioning system receiver;

(c-2) calculating a true position of said user based on said predicted position of said user and a measured position from said global positioning system receiver, wherein said true position of said user is an average position of said predictedposition of said user and said measured position from said global positioning system receiver;

(c-3) computing a distance from said true position of said user to a road neighboring said true position of said user; and

(c-4) comparing said distance from said true position of said user to said road neighboring said true position of said user with a threshold, wherein said threshold is preset based on an accuracy of said global positioning system receiver, andsaid position mark of said user is displayed on said road when said distance from said true position of said user to said road neighboring said true position of said user is less than said threshold, wherein said position mark of said user is displayedat said calculated true position when said distance from said true position of said user to said road neighboring of said true position of said user is larger than said threshold.

(b) retrieving geospatial data from a geospatial map database based on said position from said global positioning system receiver through the steps of:

(b-1) defining an access area based on said position from said global positioning system receiver and a geographic extent wherein said position from said global positioning system receiver is a center of said access area, and said geographicextent is input by a user;

(b-2) performing a GPS-based database matching process to derive an involved geospatial database, wherein said geographic extent of said access area is compared with a geographic extent of said geospatial database to check whether said accessarea is included in said geospatial database, intersects with said geospatial database, or is excluded from said geospatial database;

(b-3) performing a GPS-based involved tile finding process on said involved databases to derive involved tiles, wherein said tile is geographically subdividing a coverage solely for a purpose of enhancing data management, wherein a tile indexfile is used to retrieve a geographic extent of said tile, and said geographic extent of said access area is compared with said geographic extent of said tile to check whether said access area is included in said tile, intersects with said tile, or isexcluded from said tile; and

(b-4) performing a GPS-based primitive access process on said involved tiles, wherein said GPS-based primitive access comprises a GPS-based node access, a GPS-based edge access, and a GPS-based area access, wherein said primitive includes a nodean edge, and an area, wherein said node, said edge, and said area in said involved tiles are retrieved;

(c) displaying said retrieved geospatial data on said graphic displaying unit as a background;

(d) performing time-space filtering based on said position and said retrieved geospatial data from said geospatial map database to derive a displaying position for said user; and

(e) displaying a trajectory of said user on a graphic displaying unit, which tracks a motion of said user.

27. An enhanced global positioning system and map navigation process, as recited in claim 26, wherein the step (d) further comprises the steps of:

(d-1) forming a predicted position by predicting a next position of said user based on a current position and velocity of said user from said global positioning system receiver;

(d-2) calculating a true position of said user based on said predicted position of said user and a measured position from said global positioning system receiver, wherein said true position of said user is an average position of said predictedposition of said user and said measured position from said global positioning system receiver;

(d-3) computing a distance from said true position of said user to a road neighboring said true position of said user; and

(d-4) comparing said distance from said true position of said user to said road neighboring said true position of said user with a threshold, wherein said threshold is preset based on an accuracy of said global positioning system receiver, andsaid position mark of said user is displayed on said road when said distance from said true position of said user to said road neighboring said true position of said user is less than said threshold, wherein said position mark of said user is displayedat said calculated true position when said distance from said true position of said user to said road neighboring of said true position of said user is larger than said threshold.

(b) retrieving geospatial data from a geospatial map database based on said position from said global positioning system receiver through the steps of:

(b-1) defining an access area based on said position from said global positioning system receiver and a geographic extent, wherein said position from said global positioning system receiver is a center of said access area, and said geographicextent is input by a user;

(b-2) performing a GPS-based database matching process to derive an involved geospatial database, wherein said geographic extent of said access area is compared with a geographic extent of said geospatial database to check whether said accessarea is included in said geospatial database, intersects with said geospatial database, or is excluded from said geospatial database;

(b-3) performing a GPS-based involved tile finding process on said involved databases to derive involved tiles, wherein said tile is geographically subdividing a coverage solely for a purpose of enhancing data management, wherein a tile indexfile is used to retrieve a geographic extent of said tile, and said geographic extent of said access area is compared with said geographic extent of said tile to check whether said access area is included in said tile, intersects with said tile, or isexcluded from said tile; and

(b-4) performing a GPS-based primitive access process on said involved tiles, wherein said GPS-based primitive access comprises a GPS-based node access, a GPS-based edge access, and a GPS-based area access, wherein said primitive includes a node,an edge, and an area, wherein said node, said edge, and said area in said involved tiles are retrieved;

(c) displaying said retrieved geospatial data on said graphic displaying unit as a background;

(d) performing time-space filtering based on said position and said retrieved geospatial data from said geospatial map database to derive a displaying position for said user;

(e) displaying an accurate position of said user on said graphic displaying unit as a mark; and

(f) displaying a trajectory of said user on a graphic displaying unit, which tracks a motion of said user.

29. An enhanced global positioning system and map navigation process, as recited in claim 28, wherein the step (d) further comprises the steps of:

(d-1) forming a predicted position by predicting a next position of said user based on a current position and velocity of said user from said global positioning system receiver;

(d-2) calculating a true position of said user based on said predicted position of said user and a measured position from said global positioning system receiver, wherein said true position of said user is an average position of said predictedposition of said user and said measured position from said global positioning system receiver;

(d-3) computing a distance from said true position of said user to a road neighboring said true position of said user; and

(d-4) comparing said distance from said true position of said user to said road neighboring said true position of said user with a threshold, wherein said threshold is preset based on an accuracy of said global positioning system receiver, andsaid position mark of said user is displayed on said road when said distance from said true position of said user to said road neighboring said true position of said user is less than said threshold, wherein said position mark of said user is displayedat said calculated true position when said distance from said true position of said user to said road neighboring of said true position of said user is larger than said threshold.

a mission specific database creation module for generating a local database stored in said computing platform from said remote geospatial database;

a database updating module for adding new features using a global positioning system receiver as a basic device;

a feature attribute coding catalogue for encoding for said new features added to said geospatial database and for decoding for said GPS-based efficient geospatial database access and spatial query;

a communication interface, which provides a communication link between said remote geospatial database and said computing platform;

a data uploading module for transmitting said new features added to said database to said remote geospatial database via said communication interface; and

a data downloading module for transmitting said created mission specific database from said remote geospatial database to said computing platform.

31. An enhanced global positioning system and map navigation system, as recited in claim 30, wherein said database access and query module is adapted for performing primitive access and spatial query, wherein said primitive access includes anode access, an edge access and an area access, wherein said spatial query includes a point query, a line query and an area query.

32. An enhanced global positioning system and map navigation system, as recited in claim 31, wherein said primitive access comprises the steps of:

defining an access area based on said position from said global positioning system receiver and an geographic extent, wherein said position from said global positioning system receiver is a center of said access area and said geographic extent isinput by said user;

performing a GPS-based database matching process to derive an involved geospatial database, wherein said geographic extent of said access area is compared with a geographic extent of said geospatial database to check whether said access area isincluded in said geospatial database, intersects with said geospatial database, or excludes from said geospatial database;

performing a GPS-based involved tile finding process on said involved databases to derive involved tiles each of which is geographically subdividing a coverage solely for the purpose of enhancing data management, wherein a tile index file is usedto retrieve a geographic extent of said tile, wherein said geographic extent of said access area is compared with said geographic extent of said tile to check whether said access area is included in said tile, intersects with said tile or is excludedfrom said tile; and

performing a GPS-based primitive access process on said involved tiles, wherein said GPS-based primitive access comprises a GPS-based node access, a GPS-based edge access, and a GPS-based area access, wherein said primitive includes a node, anedge and an area, wherein said node, said edge and said area in said involved tiles are retrieved.

33. An enhanced global positioning system and map navigation system, as recited in claim 31, wherein said point query comprises the steps of:

defining a query point using said operational interface on said screen;

generating a query rectangle based on said query point;

performing a geospatial database matching by comparing a geographic extent of said query rectangle with a geographic extent of said geospatial database to derive an involved geospatial database;

performing a destination tile finding by comparing said geographic extent of said query rectangle with a geographic extent of a tile of said involved geospatial database to derive an involved tile; and

performing a node spatial information retrieval on said involved tile by using a node spatial index file.

34. An enhanced global positioning system and map navigation system, as recited in claim 31, wherein said line query comprises the steps of:

defining a query point by pointing a line of interest using said operational interface on said screen;

generating a query rectangle based on said query point;

performing a geospatial database matching by comparing a geographic extent of said query rectangle with a geographic extent of said geospatial database to derive an involved geospatial database;

performing a destination tile finding by comparing said geographic extent of said query rectangle with a geographic extent of a tile of said involved geospatial database to derive an involved tile; and

performing an edge spatial information retrieval on said involved tile by using an edge spatial index file.

35. An enhanced global positioning system and map navigation system, as recited in claim 31, wherein said area query comprises the steps of:

defining a query point by pointing an area of interest using said operational interface on said screen;

generating a query rectangle based on said query point;

performing a geospatial database matching by comparing a geographic extent of said query rectangle with a geographic extent of said geospatial database to derive an involved geospatial database;

performing a destination tile finding by comparing said geographic extent of said query rectangle with a geographic extent of a tile of said involved geospatial database to derive an involved tile; and

performing an area spatial information retrieval on said involved tile by using an area spatial index file.

(a) receiving a position of a user from a position determination device;

(b) converting a global coordinate to a local coordinate to match a coordinate system employed in a map database:

(c) retrieving geospatial data from a geospatial map database based on said measured position from said global positioning system receiver by using a tile index file which stores geographic extent information of tiles; wherein said tiles aregeographically subdividing a coverage solely for a purpose of enhancing data management; wherein a geographic extent of an access area is compared with said geographic extent of said tiles to derive a plurality of involved tiles for said access area.

(d) performing time-space filtering based on said measured position and said retrieved geospatial data from said geospatial map database to derive a displaying position for a user; wherein said measured position and a previous position and aprevious velocity are used to derive a true position for said user; and

(e) performing coordinate conversion from said local coordinate to a pixel coordinate and displaying said position of said user on a graphic displaying unit.

37. An enhanced global positioning system and map navigation system comprising:

a geospatial database which is stored on a computing platform and provides a spatial information for a user;

an operational interface for providing a command input method for said user;

an integrated menu for providing a collection of functional menus for said user;

a database updating module for adding new features using a global positioning system receiver as a basic device;

a feature attribute coding catalogue for encoding for new features added to said geospatial database and for decoding for said efficient database access and query;

a map viewer for displaying a map and a user mark on a screen, for displaying a trajectory of a motion of said user, and for zooming in and zooming out display of said geospatial data, wherein said map is generated from retrieved geospatial datain said database access and query module and displayed as background and said user mark is displayed on said screen to show a position of said user; and

a time-space filtering module for fully fusing a GPS position from said global positioning system receiver and said retrieved geospatial data in said database query and access module to derive an accurate position of said user.

38. An enhanced global positioning system and map navigation system, as recited in claim 37, wherein said database access and query module is adapted for performing primitive access and spatial query, wherein said primitive access includes anode access, an edge access and an area access, wherein said spatial query includes a point query, a line query and an area query.

39. An enhanced global positioning system and map navigation system, as recited in claim 38, wherein said primitive access comprises the steps of:

defining an access area based on said position from said global positioning system receiver and an geographic extent wherein said position from said global positioning system receiver is a center of said access area and said geographic extent isinput by said user;

performing a GPS-based database matching process to derive an involved geospatial database, wherein said geographic extent of said access area is compared with a geographic extent of said geospatial database to check whether said access area isincluded in said geospatial database, intersects with said geospatial database or is excluded from said geospatial database;

performing a GPS-based involved tile finding process on said involved databases to derive involved tiles each of which is geographically subdividing a coverage solely for the purpose of enhancing data management, wherein a tile index file is usedto retrieve a geographic extent of said tile, wherein said geographic extent of said access area is compared with said geographic extent of said tile to check whether said access area is included in said tile, intersects with said tile or is excludedfrom said tile; and

performing a GPS-based primitive access process on said involved tiles, wherein said GPS-based primitive access comprises a GPS-based node access, a GPS-based edge access and a GPS-based area access, wherein said primitive includes a node, anedge and an area, wherein said node, said edge and said area in said involved tiles are retrieved.

40. An enhanced global positioning system and map navigation system, as recited in claim 38, wherein said point query comprises the steps of:

defining a query point using said operational interface on said screen;

generating a query rectangle based on said query point;

performing a geospatial database matching by comparing a geographic extent of said query rectangle with a geographic extent of said geospatial database to derive an involved geospatial database;

performing a destination tile finding by comparing said geographic extent of said query rectangle with a geographic extent of a tile of said involved geospatial database to derive an involved tile; and

performing a node spatial information retrieval on said involved tile by using a node spatial index file.

41. An enhanced global positioning system and map navigation system, as recited in claim 38, wherein said line query comprises the steps of:

defining a query point by pointing a line of interest using said operational interface on said screen;

generating a query rectangle based on said query point;

performing a geospatial database matching by comparing a geographic extent of said query rectangle with a geographic extent of said geospatial database to derive an involved geospatial database;

performing a destination tile finding by comparing said geographic extent of said query rectangle with a geographic extent of a tile of said involved geospatial database to derive an involved tile; and

performing an edge spatial information retrieval on said involved tile by using an edge spatial index file.

42. An enhanced global positioning system and map navigation system, as recited in claim 38, wherein said area query comprises the steps of:

defining a query point by pointing an area of interest using said operational interface on said screen;

generating a query rectangle based on said query point;

performing a geospatial database matching by comparing a geographic extent of said query rectangle with a geographic extent of said geospatial database to derive an involved geospatial database;

performing a destination tile finding by comparing said geographic extent of said query rectangle with a geographic extent of a tile of said involved geospatial database to derive an involved tile; and

performing an area spatial information retrieval on said involved tile by using an area spatial index file.

Description:

FIELD OF THE INVENTION

The present invention relates generally to a geospatial database access and query method, and more particularly to a map and Global Positioning System (GPS) navigation process. With the location information provided by a GPS receiver, thegeospatial database operations, such as database access and query, are speeded up. With the map data from a geospatial database, the navigation performance and accuracy are enhanced.

BACKGROUND OF THE INVENTION

A geospatial database has a big volume of spatial and text data which are organized in a file system or in tabular fashion. The data is used by the user to query spatial information and associated features and text descriptions. Due to theamount of a geospatial database, there exists difficulty to efficiently perform database access and query.

The coordinate information is the basic element of a geospatial database. There is a need to incorporate coordinate information into the geospatial database access and query operations.

The Global Positioning System (GPS) is an all-weather, space based navigation system under development by the Department of Defense (DoD) to satisfy the requirements for the military forces to accurately determine their position, velocity, andtime in a common reference system, anywhere on the Earth on a continuous basis. To provide a continuous global positioning capability, a scheme to orbit a sufficient number of GPS satellites to ensure that four were always electronically visible wasdeveloped. The GPS receiver is used to measure the distances to the satellites. Then the location expressed as latitude, longitude and elevation are derived.

The global positioning system receiver, which includes an antenna, a signal processing unit, and associated electronics, receives signals from the global positioning system satellites to obtain position, velocity, and time solution. The globalpositioning system principle of operation is based on range triangulation. Because the satellite position is known accurately via ephemeris data, the user can track the satellite's transmitted signal and determine the signal propagation time. Since thesignal travels at the speed of light, the user can calculate the geometrical range to the satellite. The actual range measurement (called the pseudorange) contains errors, for example, bias in the user's clock relative to global positioning systemreference time. Because atomic clocks are utilized in the satellites, their errors are much smaller in magnitude than the users' clocks. Thus, for three-dimensional position determination, and also to calculate the cock bias, the pure globalpositioning system needs a minimum of four satellites to obtain the user's location.

The position accuracy provided by a GPS receiver is roughly 100 meters when only Coarse/Acquisition (C/A) code is employed and the Selective Availability (SA) is on. For personal navigation this position accuracy need to be enhanced. To obtainenhanced navigation function and accuracy, other navigation data should be incorporated in the navigation process, such as a geospatial database.

Summary of the Invention

The main objective of the present invention is to provide an enhanced navigation process, which incorporates the GPS position data and geospatial map data.

Another objective of the present invention is to provide an efficient geospatial database query and access method by using GPS position data in the geospatial data retrieval procedure.

Another objective of the present invention is to provide a time-space filtering method to fully fuse the GPS position data and the geospatial map data to obtain enhanced navigation performance.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram illustrating the GPS based geospatial database operation method according to a preferred embodiment of the present invention.

FIG. 2 is a block diagram illustrating the GPS based geospatial map navigation process according to an alternative mode of the preferred embodiments of the present invention.

FIG. 3 is a block diagram delineating the hierarchy structure of a geospatial map database which is used with a GPS receiver for enhanced navigation process.

FIG. 4 is a block diagram illustrating the database access and primitive retrieval process of a geospatial map database with aiding from a GPS position.

FIG. 5 illustrates the GPS based point query procedure of the present invention.

FIG. 6 illustrates the GPS based line query procedure of the present invention.

FIG. 7 illustrates the GPS based area query procedure of the present invention.

FIG. 8 illustrates the time-space filtering with the GPS data and the geospatial map data for enhanced navigation performance and accuracy.

The GPS-based spatial query includes the point query process, the line query process, and the area query process. These processes provide an efficient spatial query solution in geospatial database. The GPS-based mission specific databasecreation process is to perform efficient mission specific geospatial database generation.

A GPS-based geospatial database value-adding process is to perform geospatial database value-adding using a GPS receiver as the basic device for acquisition of an object's geospatial information. The GPS receiver provides an efficient method tocapture the geospatial information associated with a spatial object. A feature attribute coding catalogue 36 (FACC) provides an encoding and decoding system for the features and attributes search and adding. All the feature and attribute related filesare updated during the feature and attribute adding.

The major application of the present invention is for personal navigation, car navigation, and also can be used for access, query, updating and value-adding to a geospatial database.

The geospatial database can be a remote database, which is not stored in the navigation process platform, such as a personal computer, a notebook computer, or a palm computer. Referring to FIG. 1, an enhanced global positioning system and mapnavigation system according to a preferred embodiment of the present invention comprises an operational interface 10, a friendly integrated functional menu 20, a database query and access module 31, a mission specific database creation module 32, a datadownloading module 33, a data uploading module 34, a database updating module 35, a feature attribute coding catalogue 36, a position sensor 50, a communication interface 37, and a geospatial database 38.

The operational interface 10 provides the user with entry of commands. The operational interface 10 includes a touch screen with which the user can use his finger or a stylus to operate the embedded software, for example to perform databasequery. The operational interface 10 can also be enhanced by a soft keyboard with which the user can input commands exactly like the keyboard of a desktop computer. The operational interface 10 can also be a handwriting recognition system. The userjust write the commands on the screen to input commands. The friendly integrated functional menu 20 provides the user with involved navigation and database query functions, including map viewer, trip scheduler, GPS navigator, street locator, snaprouter, and information query. The map viewer shows an electronic map on the screen of a computer to show where the user is. The user can use scroll bar to roam the map. The trip scheduler provides trip planning function for the user. The GPSnavigator provides the user with real-time navigation information, including position, velocity, and heading. This GPS navigator has a communication interface 37 with a GPS receiver to get the GPS data. The street locator provides user with capabilityto find an address of interest. The snap router provides the user with optimized time-based or cost-based routes. For example, a delivery company will make delivery to multiple customers at the same time. The deliverer can use this snap router toobtain a delivery route based on shortest time consuming or a cheapest route, such as avoiding toll freeway.

The data updating module 35 provides new data to the geospatial database 38. The new data is uploaded to the remote geospatial database 38 through the data uploading module 34. The feature attribute coding catalogue 36 is used to encode the newadded data and features. The feature attribute coding catalogue 36 is also used to decode the data in the database query and access module 31 and the mission specific database creation module 32.

If the geospatial database 38 can be a local database stored on the GPS/Map navigation process platform, referring to FIG. 2, an alternative mode of the enhanced global positioning system and map navigation system is employed, which alsocomprises the operational interface 10, the friendly integrated functional menu 20, the database query and access module 31, the database updating module 35, and a feature attribute coding catalogue 36, and further comprises a map viewer 41 and atime-space filtering module 42.

The map viewer 41 displays the map and user mark on the screen. The user mark tracks the user's position. The user's motion trajectory can also be displayed on the screen. The map viewer 41 includes zoom in and zoom out functions. The usercan also use the map viewer 41 to roam the map.

The time-space filtering module 42 is used to fully fuse the GPS data and the geospatial map data. The time-space filtering technique is a valuable solution for enhanced navigation process which assures that the user's tracking mark is on theroad and track the user correctly and high accurately.

Global scale databases inevitably consist of large amounts of data. In processing the geographic data, entire files often need to be managed in memory, imposing a definite limit on database size. Tiling is the method used to break up geographicdata into spatial units small enough to fit within the limitations of the desired hardware platform and media.

Tiling means geographically subdividing a coverage solely for the purpose of enhancing data management, a coverage subdivided in such a manner is then referred to as a tiled coverage.

A tile index file is mandatory if a database contains tiled directories. The spatial extent of database and its tiling scheme are represented in the tile index file. A tiled coverage contains the same attribute information as an untiledcoverage. The logical interpretation of a tiled coverage is identical to that of an untiled one. Each tile will be a separate subdirectory and contains separate primitive tables for those features contained within the tile.

Primitive access for untiled coverages can be performed on the whole geographic extent of the database. Primitive access for tiled coverage will be done through two continuous procedures as follows: 1) the GPS-based tile finding procedure isapplied to find the involved tiles, and 2) the geometric and cartographic primitive access is done on the regional extent of an individual involved tile at the corresponding tile subdirectory. This GPS based primitive access strategy speeds up thesearch procedure of the primitive.

The geospatial database 38 includes a main directory in which the index file 1 (382) and tile directory reside 383. Under the tile directory there are index file 2 (384) and thematic files 385. The index file 1 provides the tile information,including tile's name, directory, and geospatial extent. The data are stored in individual tile directory. The index file 2 gives the primitive and theme information. The primitives are node, edge, and area.

Multiple databases are used to geographically cover a country or the world. The first step for the database access process is the database matching procedure. This is done by comparing the defined access area and the geospatial extent of adatabase. If the defined access area is included in or intersects with the geospatial database 38 this database will be used for data access.

The second step for the database access process is the involved tile finding procedure 313, which is used to speed up the geospatial data access. The principle of the GPS-based tile finding is to match the defined access area with the separatetiles to derive the involved tiles. The primitive (such as node, edge and face) access is only performed upon the involved tiles. This method avoids a global search for geospatial data to speed up database access processing.

The third step is the primitive access procedure 315 that is applied to perform node, edge, area, and attributes retrieval.

Geodetic Coordinate (GDC) systems are based on approximation of the shape of the Earth. The shape of the Earth was defined by classical navigators as a spherical body. More accurate geodetic coordinates require that the Earth be modeled insteadas an oblate spheroid, or an ellipsoid-of-rotation. GDCs are those that relate Earth-centered angular latitude and longitude (and optionally height) to an actual point near or on the Earth's surface.

Latitude is defined to be the angle subtended with the ellipsoid's equatorial plane by a perpendicular through the surface of the ellipsoid from a point. Latitude is positive if north of the equator, negative if south. Longitude is defined asthe angle measured about the minor (polar) axis of the ellipsoid from a prime meridian to the meridian through a point. It is positive if the point is east of the prime meridian, and negative if the point is west of the prime meridian. Unlike latitude,which has a nautical origin at the equator, there is no feature on the ellipsoid which forms a nautical origin for the measurement of longitude. The zero longitude can be any defined meridian. Historically, nations have used the meridian through theirnational astronomical observatories, giving rise to several prime meridians. By current convention, the meridian through Greenwich, England is the standard prime meridian.

The ellipsoid and the datum are the two major components of a GDC. There are many ellipsoids in use to model the Earth and each particular ellipsoid can have its location and orientation relative to the Earth defined in different ways. Thelocation and orientation of the ellipsoid with respect to the Earth is defined by the datum. World Geodetic System 1984 (WGS-84) defines the current US DoD standard datum.

The WGS-84 acts as the GPS receiver's reference system, and the Mean Sea Level (MSL) is the vertical datum. When the geospatial database 38 uses different reference system or/and vertical datum, a coordinate conversion between the differentreference systems and datum must be done.

The user location [.phi..sub.u,.lambda..sub.u ] can be derived from a GPS receiver in form of geodetic Latitude and Longitude coordinates, where .phi..sub.u is the latitude and .lambda..sub.u is the longitude. The user location can be mappedinto a point (x,y) on a plane. There are many kinds of map projections. In principle,

is the general formulation of the desired map projection, and a, b are the semi-axis of the reference ellipsoid. Geodetic applications require conformal projections to be used. Conformality means that an angle on the ellipsoid is preservedafter mapping it into the plane. More precisely, the angle included by two geodesics on the ellipsoid is preserved if the two geodesics are conformally mapped into the plane. Here, the Transverse Mercator projection is taken to perform the conformalprojection from the Ellipsoid coordinate into the Cartesian coordinate.

In this method, the ellipsoid is partitioned into 120 zones of 3.degree. longitude each. In the middle of each zone there is the central meridian. The projection cylinder is transverse to the ellipsoid and tangent along a central meridian. The developing cylinder, that is opened to make a plane, yields a straight line for the central meridian with no scale distortion. In a plane, the mapped central meridian represents the y-axis (north direction). The x-axis is the mapping of theequator. In the mapping of a zone, the central meridian and the equator are special cases since all other meridians and parallels are mapped as curved lines. Because of conformality, the mapped images of the meridians and parallels are orthogonal toeach other. The numbering of the zones is related to the Greenwich meridian. The mapping formulas for the Transverse Mercator projection are given by ##EQU1##

On purpose, y is given first and then x, because the pair of coordinates (y,x) corresponds to (.phi.,.lambda.). The arc length of the meridian B(.phi.) is the ellipsoidal distance from the equator to the point to be mapped and can be computed bythe following series expansion:

The range of user interest is represented by [r.sub.x,r.sub.y ], where r.sub.x is the user-defined range along the longitude axis, and r.sub.y is the user-defined range along the latitude axis. The geographic extent of the user-defined accessarea in degrees is derived by the following procedures:

The objective of Step 1 is mapping a point (.phi.,.lambda.) on the ellipsoid into a point (x,y) on a plane. This can be done by applying Equation (2). Step 2 is computed by the following procedure:

where the symbol .sym. represents the following operations:

Step 3 is the inverse procedure of the Step 1, that is the transformation of a point (x,y) in the plane to a point (.phi.,.lambda.) on the ellipsoid. The principle methodology is the same, the coordinates on the ellipsoid are obtained fromseries expansions: ##EQU3##

The terms with the subscript f must be calculated based on the footpoint latitude .phi..sub.f. For the footpoint latitude, the series expansion

is used where

the coefficients .alpha., .beta., .gamma., .delta. depend on the ellipsoid parameters. The preferred values are the parameters for the Bessel ellipsoid:

Assume that [.phi..sub.min,.lambda..sub.min ; .phi..sub.max,.lambda..sub.max ] represents the geographic extent of a regional geospatial database 38. The GPS-based database matching is given by

with a BOOL value output. When the given database is involved, the BOOL is TRUE (1) or the BOOL is FALSE (0). The symbol .times. represents the following operations:

When the inequalities .lambda..sub.min <.lambda..sub.u min <.lambda..sub.max & .phi..sub.min <.phi..sub.u min <.phi..sub.max are met, the left-lower corner of the user-defined access area is contained in the given regional database. When the inequalities .lambda..sub.min <.lambda..sub.u min <.lambda..sub.max & .phi..sub.min <.phi..sub.u max <.phi..sub.max are met, the left-upper corner of the user-defined access area is contained in the given regional database. When theinequalities .lambda..sub.min <.lambda..sub.u max <.lambda..sub.max & .phi..sub.min <.phi..sub.u max <.phi..sub.max are met, the right-upper corner of the user-defined access area is contained in the given regional database. When theinequalities .lambda..sub.min <.lambda..sub.u max <.lambda..sub.max & .phi..sub.min <.phi..sub.u min <.phi..sub.max are met, the right-lower corner of the user-defined access area is contained in the given regional database. When theinequalities .lambda..sub.u min <.lambda..sub.min,.lambda..sub.max <.lambda..sub.u max & .phi..sub.u min <.phi..sub.min, .phi..sub.max <.phi..sub.u max are met, the given database is wholly contained by the user-defined access area.

Assume that [.phi..sub.min,.lambda..sub.min ; .phi..sub.max,.lambda..sub.max ].sub.ti represents the geographic extent of tile i. The GPS-based involved tile finding is given by

with a BOOL value output. When the given tile is involved, the BOOL is TRUE (1) or FALSE (0). The symbol .times. conforms to the operations given by Equation (11).

Only the involved tiles will be considered during the primitive access. The primitives, such as the nodes, edges, faces and text, which are included in the involved tiles, will be further considered whether it is involved within the user-definedaccess area or not.

Connected nodes are always found at the ends of edges and are topologically linked to the edges. Connected nodes are used in two ways: to define edges topologically, and to represent point features, such as overpasses, locks in a canal, orunderground utility access points. Under the first usage, the connected nodes are referred to as start and end nodes. Under the second usage, attributes will be associated with the point features related to the connected nodes.

A simple mathematical comparison is taken to determine whether the given node in an involved tile is included in the access area. If it is, this node will be used to retrieve the topological relationships with other primitives. If not, thisnode will be neglected in the further topographic processing. The access area is given by [.phi..sub.u min,.lambda..sub.u min ; .phi..sub.u max,.lambda..sub.u mx ]. The comparison is given by

Edges are one-dimensional primitives that are used to represent the locations of linear features (such as roads) and the borders of faces. Edges are comprises an ordered collection of two or more coordinate tuples (pairs or triplets). At leasttwo of the coordinate tuples must be distinct. The orientation of an edge is defined by the ordering of the coordinate tuples.

Edges are topologically defined by nodes. Then areas are defined by edges. In addition to the Start Node and End Node columns in an edge primitive file, the Right Edge, Left Edge Right Face and Left Face are necessary to support highertopological levels. The topology information permits the query and retrieval of features. The direction of an edge is its orientation from the Start Node to the End Node. Each edge primitive table has an associated Edge Bounding Rectangle (EBR) tablewhich contains the MBR information for every edge. There is a one-to-one relationship between the edge table and its associated Edge Bounding Rectangle Table.

The access area is given by [.phi..sub.u min,.lambda..sub.u min ; .phi..sub.u max, .lambda..sub.u max ]. Assume that [.phi..sub.e min,.lambda..sub.e min ; .phi..sub.e max,.lambda..sub.e max ] represents the edge bounding rectangle. The involvededge finding is algorithm is given by

with a BOOL value output. When the given edge is involved, the BOOL is TRUE (1) or FALSE (0). The operator .times. conforms to the following operation:

A face primitive is a two-dimensional spatial object enclosed by edges. Faces are used to represent area features, such as lakes, countries, or urban areas. Faces are defined by topological references to a set of edges that compose the faceborder. A face may have interior borders as well as exterior borders, allowing for faces that have other smaller faces within them. This relation consists of a reference to the start of a closed ring of edges. A face may consist of multiple rings. Only one outer ring will be assigned to a face. Faces are non-overlapping, and the faces in a coverage completely exhaust the area of a plane. Each face table has a related Face Bounding Rectangle (FBR) table which contains the MBR information for eachface. There is a one to one relationship between the face table and the associated FBR table.

The access area is given by [.phi..sub.u min,.lambda..sub.u min ; .phi..sub.u max,.lambda..sub.u max ]. Assume that [.phi..sub.f min,.lambda..sub.f min ; .phi..sub.f max,.lambda..sub.f max ] represents the face bounding rectangle. The involvedface finding algorithm is given by

with a BOOL value output. When the given face is involved, the BOOL is TRUE (1) or FALSE (0). The operator .times. conforms to the operation given by Equation (15).

A spatial query is the procedure used to obtain or capture the features and attributes related to a spatial object, such as point, line and/or area, through a geospatial database access. The spatial object is defined through the user points at aspecific position on a display device containing a graphic representation of the data. In order to get the information about the spatial object, the query algorithm must search the primitive table for an exact match with this object.

The GPS-based database query comprises three types of spatial query: GPS-based point query, GPS-based line query, and GPS-based area query. Basically, the GPS based spatial object queries comprises a 2-step search procedure, which are 1)destination tile finding, and 2) spatial query using, the spatial index file.

In order to use the spatial index in the spatial queries, it is necessary to find the involved tiles during spatial queries because the spatial index file pertains to the tile directory. Tiles maintain spatially distributed primitives inseparate directories. Thus, the query can be done for a tiled database in only the relevant tile after the appropriate tile has been identified.

The results from the GPS based efficient geospatial data access can be directly used to reduce the spatial search range for object queries. Suppose that the involved databases are represented as D.sub.i (i=1,2,.LAMBDA.,n). These databases arewith respect to the extent [.phi..sub.min,.lambda..sub.min ; .phi..sub.max,.lambda..sub.max ], where n is the number of involved databases. The involved tiles in the databases D.sub.i are T.sub.i.sup.j (j=1,2,.LAMBDA.,m.sub.i), where m.sub.i is thenumber of involved tiles in the database D.sub.i.

The first step in destination tile finding is the database matching procedure done on the involved database. The involved databases are given by the GPS-based database matching process. The database matching for spatial queries is performedonly on these involved databases. Denote the coordinates of a point on the display device as [x.sub.s, y.sub.s ] in the screen plane coordinate system, where the origin is at the upper-left corner of the screen. The coordinates of the upper-left screencorner in the Cartesi an Coordinate System are denoted as [x.sub.0, y.sub.0 ]. The corresponding Cartesian coordinate of the position on the screen is given by the following vector sum:

In Equation (17) k.sub.1 and k.sub.2 are the scale factor along the horizontal and vertical axis, respectively. Normally the relation k.sub.1 =-k.sub.2 holds.

Next, the transformation of the point [x, y] in the plane to the point [.phi., .lambda.] on the ellipsoid is made. The coordinates on the ellipsoid are obtained through a series expansion as shown in Equations 6-9.

The database matching algorithm for spatial query is given by

with a BOOL value output. In Formula (18) the number n represents the total number of databases involved. When the primitive queried is contained in the database, the BOOL is to TRUE (1). When the primitive queried is not contained in thedatabase, the BOOL is FALSE (0). The symbol o represents the following operations:

The spatial query will be performed on the database which makes Formula (19) return TRUE.

The second step in the destination tile finding procedure is tile matching. The involved tiles are given by the GPS-based involved tile finding process. The tile matching for spatial queries are performed only on these involved tiles. Thecorresponding area to an individual tile can be indexed according to the index file 1.

Assuming that [.phi..sub.min,.lambda..sub.min ; .phi..sub.max,.lambda..sub.max ].sub.ti represents the geographic extent of the tile, the tile matching process is given by

with a BOOL value output. When the primitive queried is contained in the tile, the BOOL is set to TRUE (1), else the BOOL is FALSE (0). The symbol o represents the operations given by Formula (19).

The second step in the GPS based spatial query is to use the appropriate spatial index file for spatial information retrieval. It is necessary for the algorithm to exhaustively check nodes and text primitives for satisfaction of a spatial query,since these primitives do not have associated minimum bounding rectangles. The coordinates of the primitive are used to ensure the accurate retrieval of primitive ids from the spatial index.

Point query is aimed at finding the node (connected or entity) in the vicinity of the query point. The vicinity area is defined as a circle on the screen with a radius R and centered at the query point. The radius R is given with a specificnumber of pixels.

Based on the corresponding node index file 65, the ids of nodes which are located in the vicinity of the query point will be retrieved. Using these node ids, the corresponding geodetic coordinates can be obtained. Further point query processingis done to get the features and attributes associated with the queried nodes. The features and attributes can be reported in text format.

Suppose that the corresponding geodetic coordinate of the query point is given by [.phi..sub.o,.lambda..sub.o ], which can be derived from its screen coordinate through the transformation given by Equations (6) through (9). This coordinate isconverted into the spatial index coordinate system as follows: ##EQU4##

where the operator int is to get the integer part, x.sub.O is the normalized coordinate along the horizontal axis; y.sub.o is the normalized coordinate along the vertical axis; .phi..sub.max, .phi..sub.min,.lambda..sub.max and .lambda..sub.minare given in the header of the node index file, which defines the Minimum Bounding Rectangle.

The circle on the screen is converted into a query rectangle (QR) in the spatial index coordinate system. This procedure is done in the query rectangle generation module. The nodes contained in this rectangle will be queried.

The four 1-byte integers defining the MBR [x.sub.n min, y.sub.n min ; x.sub.n max,y.sub.n max ] for a node primitive are given in the node index file. The relationships x.sub.n max -x.sub.n min.ltoreq.1 and y.sub.n max -y.sub.n min.ltoreq.1 holdfor the node primitive. The following operations are used to determine whether a node is contained in the query rectangle:

The symbol I represents the intersection set of the query rectangle and the MBR for a node primitive. A BOOL value of TRUE means that the given node is contained in the query rectangle.

Line query is aimed at finding the edges in the vicinity of the query point. The vicinity area is also defined as a circle on the screen with a radius R and centered at the query point. The radius R is given with a specific number of pixels. Referring to FIG. 6, the edge query comprises a query point selection 71, a query rectangel generation 72, a matching database 73, an involved tile 74, an edge index files 75, and an attribute retrieval module 77.

Based on the corresponding edge index file 75, the ids of the edges located in the vicinity of the query point will be retrieved. With these edge ids and the corresponding edge file, the edges and the corresponding geodetic coordinates of theconnected nodes can be obtained. Further line query processing is done to get the features and attributes associated with the queried edges. The features and attributes can be reported in text format.

The circle on the screen is converted into a query rectangle (QR) in the spatial index coordinate system. This is done in the query rectangle generation module 73. The edges whose MBR intersect the query rectangle will be queried.

The four 1-byte integers defining the MBR [x.sub.e min, y.sub.e min ; x.sub.e max, y.sub.e max ] for an edge primitive are given in the edge index file. The following operations are used to determine whether an edge MBR intersects the queryrectangle:

A BOOL value of TRUE means that the given edge intersects the query rectangle.

Based on the edge ids derived from the edge index file, the edges can be retrieved from the corresponding edge primitive table.

Area query is aimed at finding the faces in the vicinity of the query point. A simpler query operation can be used for area query. This process determines whether the query point is contained in the area defined by the face primitive. Thefirst step is to get the ids for the faces whose MBR includes the query point from the face index file. Then the faces are retrieved based on the face ids. The ring table can be used here to get the geographical area defined by the retrieved face. Theconclusion is made in the end on whether the query point is contained in this area. If so, the corresponding face will be queried. Referring to FIG. 7, the area query comprises a query point selection 81, a query rectangel generation 82, a matchingdatabase 83, an involved tile 84, an area index files 85, and an attribute retrieval module 87. The area query process follows:

Step 1: Determine the faces whose MBRs contain the query point.

Suppose that the MBR for a face is represented as [x.sub.f min, y.sub.f min ; x.sub.f max, y.sub.f max ], which is given in the face index file. The following operation is used to determine the faces containing the query point.

Here the [x.sub.o, y.sub.o ] represents the normalized coordinate for the query point in the spatial index coordinate system.

Step 2: Retrieve the ring relating to the face.

The ids derived from the face index file are used to retrieve the associated ring ids from the face primitive file.

Step 3: Retrieve the area defined by a face.

The ring file provides a start edge for the face. Then travel to the left edge and read the left edge. The procedure is performed until a return to the start edge.

Step 4: Determine whether the query point is included in the retrieved area.

With these retrieved face ids, the corresponding geographic location can be obtained through retrieving the corresponding rings and the associated edges through the winged topological relationship retrieval. The further area query processing isaccomplished to get the features and attributes associated with the queried faces. The associated area feature table will be used to check what features are related to a given face. The area features are given by feature attribute code catalogue.

The retrieved geospatial data is displayed on the screen. The data include entity node, line, and area. The entity node includes school, hospital, gas station, bank, restaurant, etc. The line primitive includes road, street, freeway, river,etc. The area includes park, lake, etc. These map data can be integrated with GPS data to provide enhanced navigation performance and accuracy.

FIG. 8 illustrates the time-space filtering process for fully fusion of GPS data and the map data. This time-space filtering process is mainly used for tracking of the user's position in real time. When the user is travelling on the freeway,the user's position mark might be not displayed on the freeway due to the position error of a GPS receiver. This phenomena can be avoided by introducing the time-space filtering algorithm.

The time-space filtering process comprises a geospatial database 38, a road retrieval module 421, a position sensor 50, a position estimation and prediction module 422, a map matching process module 423, and a position display module 424.

The position sensor provides the user's current position and velocity. The position sensor 50 can be a GPS receiver. Based on the measurements of the current position and velocity the user's next position and velocity are estimated andpredicted in the position estimation and prediction module 422. The predicted user's next position is output to the map matching process module 423. The road retrieval module 421 obtains the road information in the vicinity of the user from thegeospatial database 38. The road data is output the map matching process module 423. The map matching process also receives the user's position measured by the position sensor.

The user's true position is provided by the following process:

where P.sub.t is the true position, P.sub.p is the predicted position calculated in the position estimation and prediction module 422, P.sub.m is the user's position measured by the position sensor.

The user's true position is further fused with the road data to enhance the navigation performance. A threshold is preset to check whether the user is on the road or not. The threshold is set based on the accuracy of the position sensor. Usually average error of the position sensor can be used as the threshold. When distance from the user's true position to the road is less than the threshold, the user's tracking mark will be moved from the calculated true position to the road. This isreasonable to understand that the user must be travelling on the road. If distance from the user's true position to the road is larger than the threshold, the user's tracking mark will be displayed at the calculated true position.

A method for enhanced GPS/Map navigation process can be realized under Arc/View environment. Arc/View is a software package for mapping from ESRI (Environmental Systems Research Institute), Inc.

(a) receiving a position from a position determination device such as a global positioning system (GPS) receiver;

(b) retrieving geospatial data from a geospatial map database based on the position from the position determination device;

(c) performing time-space filtering based on the position and the retrieved geospatial data from the geospatial map database to derive a displaying position for a user; and

(d) displaying the user's position on a graphic displaying unit such as a screen.

The enhanced global positioning system and map navigation process of the present invention further the step of:

before the step (c), displaying the retrieved geospatial data on the graphic displaying unit, and

after the step (c), displaying an accurate position of the user on the graphic displaying unit as a mark, wherein the retrieved geospatial data is displayed as a background.

The step (b) further comprises the steps of:

(b-1) defining an access area based on the position from the position determination device and a geographic extent, wherein the position from the position determination device is a center of the access area, and the geographic extent is input bythe user;

(b-2) performing a database matching process to derive involved geospatial database, wherein the geographic extent of the access area is compared with a geographic extent of the geospatial database to check whether the access area is included inthe geospatial database, intersects with the geospatial database, or is excluded from the geospatial database;

(b-3) performing an involved tile finding process on the involved databases to derive involved tiles, wherein the tile is geographically subdividing a coverage solely for the purpose of enhancing data management, wherein a tile index file is usedto retrieve a geographic extent of the tile, and the geographic extent of the access area is compared with the geographic extent of the tile to check whether the access area is included in the tile, intersects with the tile, or is excluded from the tile;and

(b-4) performing primitive access process on the involved tiles, wherein the primitive access comprises a node access, an edge access, and an area access, wherein the primitive includes a node, an edge, and an area, wherein the node, the edge,and the area in the involved tiles are retrieved.

The step (c) comprises the steps of

(c-1) predicting the user's next position based on the user's current position and velocity from the position determination device;

(c-2) calculating the user's true position based on the predicted user's position and a measured position from the position determination device, wherein the user's true position is an average position of the predicted user's position and themeasured position from the position determination device;

(c-3) computing a distance from the user's true position to a road neighboring the user; and

(c-4) comparing the distance from the user's true position to the road neighboring the user with a threshold, wherein the threshold is preset based on the accuracy of the position determination device, and the user's position mark is displayed onthe road when the distance from the user's true position to the road neighboring the user is less than the threshold, wherein the user's position mark is displayed at the calculated true position when the distance from the user's true position to theroad neighboring of the user is larger than the threshold.

According to the present invention, the enhanced global positioning system and map (GPS/Map) navigation system is employed to processed the above navigation process, wherein the enhanced GPS/Map navigation system comprises:

(1) a remote geospatial database 38 which is stored on a remote computer system, wherein the remote computer system is connected with a computing platform for the enhanced GPS/Map navigation process via a data link;

(2) an operational interface 10, which provides a command input method for a user;

(3) an integrated menu 20, which provides a collection of functional menus for the user;

(5) a mission specific database creation module 32, which is responsible for generating a local database stored in the computing platform for the enhanced global positioning system and map navigation process from the remote geospatial database;

(6) a database updating module 35, which provides a method for adding new features using a GPS receiver as a basic device;

(7) a feature attribute coding catalogue 36, which is used for encoding for the new features added to the geospatial database and for decoding for the efficient database access and query;

(8) a communication interface 37, which provides a communication link between the remote geospatial database and the computing platform for the enhanced global positioning system and map navigation process;

(9) a data uploading module 34, which is responsible for transmitting the new features added to the database to the remote geospatial database via the communication interface 37;

(10) a data downloading module 33, which is responsible for transmitting the created mission specific database from the remote geospatial database to the computing platform for enhanced GPS/Map navigation process.

According to an alternative mode of the present invention, for applications where specific map data is applied, an alterative mode of the enhanced global positioning system and map (GPS/Map) navigation process comprises the steps of:

(a) receiving a position of a user from a position determination device;

(b) converting a global coordinate to a local coordinate to match a coordinate system employed in a map database;

(c) retrieving geospatial data from a geospatial map database based on the position from the position determination device to form retrieved geospatial data;

(d) performing time-space filtering based on the position and the retrieved geospatial data from the geospatial map database to derive a displaying position for a user; and

(e) performing coordinate conversion from the local coordinate to a pixel coordinate and displaying the position of the user on a displaying unit.

Also, an alternative mode of the enhanced global positioning system and map navigation system to be employed for processing the above alternative navigation process comprises:

(1) a geospatial database 38 is stored on a computing platform for the enhanced GPS/Map navigation process and provides a spatial information for a user;

(2) an operational interface 10, which provides a command input method for the user;

(3) an integrated menu 20, which provides a collection of functional menus for the user;

(5) a database updating module 35, which provides a method for adding new features using a GPS receiver as a basic device;

(6) a feature attribute coding catalogue 36, which is used for encoding for the new features added to the geospatial database and for decoding for the efficient database access and query 31;

(7) a map viewer 41 for displaying a map and a user mark on a screen, for displaying trajectory of user's motion, and for zooming in and zooming out display of the geospatial data 38, wherein the map is generated from retrieved geospatial data inthe database access and query module 31 and displayed as background, the user mark is displayed on the screen to show a position of the user;

(8) a time-space filtering module 42 for fully fusing a GPS position from a GPS receiver and the retrieved geospatial data in the database query and access module 31 to derive an accurate position of the user.